Various illumination optical systems are currently proposed as the illumination optical system used in a projector such as an LED (Liquid Crystal Display) projector or a DLP (Digital Light Processing) projector.
Japanese Unexamined Patent Application Publication No. 2010-237443 (hereinbelow referred to as Patent Document 1) and Japanese Unexamined Patent Application Publication No. 2010-256457 (hereinbelow referred to as Patent Document 2) disclose illumination optical systems and projectors in which a fluorophore is irradiated by an excitation light to obtain light emission of a predetermined wavelength band from a fluorophore.
The illumination optical system (light source device) disclosed in each of these patent documents is equipped with a light source that irradiates laser light of the blue wavelength band and a light-emitting wheel on which is provided a light-emitting substance that emits light with light irradiated from the light source as excitation light. The light-emitting wheel is provided with: a red region in which a light-emitting substance is provided that emits light of the red wavelength band when excited by light from the light source, a green region in which a light-emitting substance is provided that emits light of the green wavelength band, and a blue region that transmits light of the blue wavelength band. The light-emitting substances of the light-emitting wheel are formed on a reflection layer.
The light-emitting wheel is configured so as to be rotatable. Due to the rotation of the fluorophore wheel, blue light that is emitted from the light source successively irradiates the red region, the green region, and the transmission region of the light-emitting wheel. The red light and green light generated from the fluorophores are reflected by the reflection layer.
Red light and green light that are reflected by the reflection layer and blue light that is transmitted by the transmission region are combined by a dichroic mirror or relay optical system. The combined light is irradiated upon a digital mirror device (DMD). Light of each color that is emitted in time divisions by the light-emitting wheel is spatially modulated according to input images by the DMD and projected by way of a projection lens onto a screen.